Former Cardiff winger Parry remains sidelined with a knee problem while midfielder Barry Nicholson (broken leg) is a long-term absentee.
However, defender Youl Mawene has been making steady progress after suffering knee ligament damage during the 1-0 defeat to Newcastle in November.
He has trained this week and could come into contention for the 23,000 sell-out clash in new boss Ferguson's first home match in charge.
Preston defender Neal Trotman has completed his loan move to League One outfit Huddersfield until the end of the season.
Ferguson said: "We are going to have to be at our maximum and Chelsea need to have an off day if we are to have a chance."